GIFT  OF 


The  University  of  Chicago 

Founded  by  JOHN  D.  ROCKEFELLER 


The  CrSaccharinic  Acids.     I.    The  Resolu 

tion  of  J/-2,3-Dioxybutyric  Acid  into  the 

Optically-Active  Components.     The 

Derivatives  of  These  Acids 


A  DISSERTATION 


SUBMITTED  TO  THE  FACULTY  OF  THE  OGDEN  GRADUATE 

SCHOOL  OF  SCIENCE  IN  CANDIDACY  FOR  THE 

DEGREE  OF  DOCTOR  OF  PHILOSOPHY 


DEPARTMENT  OF  CHEMISTRY 

By  GEORGE  ELMER  MILLER 


EASTON,  PA.: 

PRESS  OF  THE  ESCHENBACH  PRINTING  CO. 
1920 


The  University  of  Chicago 

Founded  by  JOHN  D.  ROCKEFELLER 


The  C4-Saccharinic  Acids.     I.   The  Resolu 
tion  of  J/-2,3~Dioxybutyric  Acid  into  the 

Optically- Active  Components.     The 
Derivatives  of  These  Acids 


A  DISSERTATION 


SUBMITTED  TO  THE  FACULTY  OF  THE  OGDEN  GRADUATE 

SCHOOL  OF  SCIENCE  IN  CANDIDACY  FOR  THE 

DEGREE  OF  DOCTOR  OF  PHILOSOPHY 


DEPARTMENT   OF   CHEMISTRY 


By  GEORGE  ELMER  MILLER 


EASTON,  PA.: 

PRESS  OF  THE  ESCHENBACH  PRINTING  CO. 
1920 


THE    C4-SACCHARINIC    ACIDS.     I.   THE    RESOLUTION    OF  dl- 
2,3-DIOXYBUTYRIC  ACID  INTO  THE   OPTICALLY-ACTIVE 
COMPONENTS.     THE  DERIVATIVES  OF  THESE  ACIDS.1 

The  saccharinic  acids  are  acids  which  would  result  from  the  oxidation 
of   the    H  — C  =  O    group    of    an    aldo-monosaccharide    of   the   formula 

CnH2wOn    to    the    O  =  C  —  OH    groug    at    the    expense    of    one, of  the 

I  I  I 

H  —  C  —  OH    groups    which    would    be     reduced    to    the    H  —  C  —  H 

I  •  I 

group.  These  acids  have  the  same  molecular  formula  as  the  correspond- 
ing aldo-monosaccharides  and  may  thus  be  looked  upon  as  the  results  of 
an  internal  oxidation-reduction  reaction.  The  saccharinic  acids  formed 
from  some  of  the  pentoses  and  hexoses  have  been  the  direct  subject  of 
study2  by  Xef  and  his  students  at  various  times,  and  have  also  entered 
into  consideration  in  connection  with  all  the  sugar-oxidation  experiments 
conducted  in  this  laboratory  in  recent  years.  These  oxidations  were 
carried  out  in  alkaline  solution,  under  which  conditions  the  production  of 
saccharinic  acids  was  a  possibility.  In  a  recent  paper  from  this"  labora- 
tory3 there  was  reported,  in  the  oxidation  of  maltose  in  alkaline  solution, 
the  production  of  an  acid,  the  phenylhydrazid  of  which  gave  a  perfect 
analysis  for  that  of  a  4-carbon-atom  saccharinic  acid.  The  properties 
of  the  free  acid  furthermore  were  those  which  would  be  expected  of  one  of 
these  acids.  Its  configuration  could  not  be  reported  because  of  lack  of 

1  Reprinted  from  an  article  in  the  Journal  of  the  American  Chemical  Society  for 
November,  1920,  by  J.  W.  E.  Glattfeld  and  G.  E.  Miller. 

2  Nef,  Ann.,  376,  1-120  (1910). 

3  /.  Am.  Chem.  Soc.,  40/973  (1918). 


458682 


data  as  to  the  properties  and  constants  of  the  4-carbon-atom  saccharinic 
acids. 

Nef  has  referred1  to  the  handicap  which  this  lack  of  data  has  imposed  on 
the  work  with  sugars  in  alkaline  solution.  In  order  to  supply  some  of  this 
deficiency  we  have  attempted  the  preparation  of  the  saccharinic  acids  in  a 
systematic  way  and  have  started  with  the  C4-saccharinic  acids  to  throw 
light  on  the  first  question  of  interest  in  this  connection,  namely,  which 
of  the  possible  optically-active  Ci-saccharinic  acids  is  formed  in  the 
oxidation  of  maltose  in  alkaline  solution.  The  present  paper  is  a  report 
on  the  preparation  of  the  first  pair  of  saccharinic  acids,  the  2,3-dioxy- 
butyric  acids.  Work  on  the  preparation  of  the  other  8  active  acids  is 
now  in  progress. 

The  dl-2, 3 -dioxy -butyric  acid  has  been  prepared  by  Hanriot.2  The 
synthesis  was  repeated  by  Nef3  who  studied  the  acid  in  somewhat  more 
detail  and  reported  a  few  of  its  properties  as  well  as  those  of  the  phenyl- 
hydrazid  and  brucine  salt.  The  constitution  of  the  d/-acid  was  proved  by 
Nef3  by  the  method  of  synthesis  and  by  oxidation  to  malic  acid.  We 
prepared  our  acid  in  accordance  with  the  procedure  of  these  investigators. 
The  analysis  of  the  vacuum-dried  barium  salt  showed  the  substance  to  be 
pure.  The  acid  was  finally  obtained  by  precipitating  the  barium  from  an 
aqueous  solution  of  the  salt  quantitatively  by  means  of  sulfuric  acid. 
The  solution  of  the  acid  was  subjected  to  complete  distillation  in  vacuo 
and  the  acid  was  then  obtained  as  a  slightly  yellow  oil.  It  was  freed 
from  inorganic  salt  by  repeated  solution  in  ethyl  acetate,  and  was  then 
used  in  the  resolution  described  below. 

The  phenylhydrazid  was  made  according  to  Nef's  directions.3  After 
many  recrystallizations  it  was  found  to  melt  at  100-101°  instead  of  at 
99°  as  reported  by  Nef. 

In  order  to  prove  that  the  acid  was  actually  d/-2,3-dioxy-butyric  acid 
it  was  prepared  also  from  vinylacetic  acid  CH2  :  CHCH2COOH  by 
oxidation  with  permanganate.  The  vinylacetic  acid  was  prepared  accord- 
ing to  the  directions  of  Hauber4  and  oxidized  according  to  the  directions 
of  Penschuk.5  The  acid  so  prepared  gave  a  phenylhydrazid  which  melted 
at  100-101°.  A  mixed  melting-point  determination  of  this  phenyl- 
hydrazid with  the  one  from  the  dl-acid  above,  showed  them  to  be  identical. 

Fichter  and  Sonneborn6  also  prepared  the  2,3-dioxy  acid  from  vinyl- 
acetic  acid  by  the  above  method  and  state  that  the  acid  is  identical  with 
that  made  by  Hanriot  from  the  a-chlorohydrine.  As  they  base  their 

1  Nef,  Ann.,  376,  9  (1910). 

2  Hanriot,  Ann.  chim.  phys.  [5]  17,  62  (1879). 
8  Nef,  Ann.,  376,  35  (1910). 

4  Hauber,  Ber.,  36,  2897  (1903). 

6  Penschuk,  Ann.,  283,  109  (1894). 

8  Fichter  and  Sonneborn,  Ber.,  35,  942  (1902). 


statement  only  on  the  analysis  of  the  barium  salt  for  barium  oxide,  which 
would  obviously  be  the  same  for  the  barium  salts  of  all  dioxy-butyric 
acids,  they  cannot  be  said  to  have  proved  the  identity  of  the  acids  from  the 
two  sources.  It  was,  therefore,  considered  necessary  to  make  the  proof 
of  the  identity  absolute  by  preparing  the  phenylhydrazids  and  proving 
them  identical  before  proceeding  with  further  studies  of  the  acid. 

The  Resolution  of  the  dl-2,3  Dioxy-butyric  Acid  into  the  Active  Com- 
ponents. 

Brucine,  cinchonine,  quinine  and  strychnine  were  tried  and  brucine 
found  to  be  best  for  the  resolution.  The  brucine  salt  was  made  in  the 
usual  way1  by  adding  a  slight  excess  of  the  alkaloid  to  an  aqueous  solu- 
tion of  the  acid  and  heating  the  mixture  on  the  water-bath.  The  use 
of  an  electrically-driven  mechanical  stirrer  greatly  hastened  the  solution 
of  the  alkaloid. 

Eighty-three  g.  of  the  dl-acid  and  305  g.  of  brucine  were  heated  in  about 
2  liters  of  water  on  the  boiling  water-bath  until  the  solution  reacted 
alkaline  to  litmus.  Three  g.  of  brucine  did  not  go  into  solution.  After 
extraction  with  benzol  and  subjection  of  the  extracted  solution  to  complete 
vacuum  distillation,  337  g.  of  crude  brucine  salt  was  obtained.  This 
was  treated  with  750  cc.  of  boiling  absolute  alcohol.  Fifteen  g.  of  floccu- 
lent  material  remained  undissolved.  This  material  was  separated  by  hot 
filtration.  The  clear  filtrate  was  allowed  to  stand  overnight  and  deposited 
crystals  which  weighed  58.4  g.  The  mother  liquor  was  subjected  to  com- 
plete vacuum  .distillation  at  60°.  The  residue,  weighing  257.5  g.,  was 
dissolved  in  300  cc.  of  boiling  absolute  alcohol.  This  solution  deposited 
crystals  which  weighed  13.55  g-  The  mother  liquor  from  the  second 
crop  was  subjected  to  complete  vacuum  distillation  at  70°.  The  residue 
weighed  204  g.  This  was  treated  with  140  cc.  of  boiling  alcohol.  This 
solution  deposited  a  third  crop  of  crystals  which  weighed  54.8  g.  A 
fourth  crop  of  crystals  which  weighed  17  g.  was  obtained  in  the  same 
way  by  treating  the  residue,  which  weighed  141  g.,  with  72  cc.  of  hot 
absolute  alcohol.  The  mother  liquor  from  the  fourth  crop  was  sub- 
jected to  complete  vacuum  distillation.  The  residue  weighed  130  g. 
No  more  crystals  could  be  obtained. 

The  rotations  of  these  4  crops  of  brucine  salts  were  taken  in  exactly 
4%  aqueous  solution.  The  density  of  the  solution  was  considered  to  be 
i.on.  The  following  results  were  obtained. 

[i20  a  in  one 

<*JD-  dcm.  tube. 

I — 29.42  — I.I9 

II — 27.95  —1.12 

III — 27.95  — I  -12 

IV — 26  .95  — i  . OQ 

1  J.  Am.  Chem.  Soc.,  40,  976   (1918).     Footnote. 


The  rotation  of  the  successive  crops  of  brucine  salts  convinced  us  that 
a  partial  separation  of  the  dl-acid  into  its  optical  components  had  been 
effected.  Our  next  effort  was,  therefore,  to  obtain  the  less  soluble  brucine 
salt  in  its  purest  form.  Another  quantity  of  crude  brucine  salt  was  pre- 
pared and  recrystallized  as  above.  Again  the  specific  rotation  of  the 
first  crop  was  — 29.42°.  The  successive  crops  had  approximately  the 
same  rotations  as  the  corresponding  ones  in  the  first  experiment.  The 
salt  with  the  specific  rotation  of  — 29.42  °  was  now  dissolved  in  the  smallest 
possible  quantity  of  hot  absolute  alcohol.  The  solution  deposited  a 
crop  of  crystals  whose  specific  rotation  was  taken.  This  crop  was  again 
dissolved  in  the  smallest  possible  quantity  of  absolute  alcohol  and  allowed 
to  stand  overnight  during  which  time  it  deposited  a  crop  of  crystals, 
which  was  separated  by  filtration  and  dried  to  constant  weight  in  vacua 
over  sulfuric  acid.  The  rotation  of  this  crop  was  taken.  This  process 
was  repeated  7  times.  The  rotations  of  the  successive  crops  were  in- 
variably between  — 29.18°  and  — 29.42°.  It  was,  therefore,  concluded 
that  the  pure  brucine  salt  of  one  of  the  optical  isomers  had  the  specific 
rotation  of  approximately  — 29.42°. 

The  Free  Acid  from  the  Brucine  Salt,  [Q:]DO,  — 29.42°. — One  hundred 
and  thirty-seven  g.  of  the  brucine  salt,  [a]™  — 29.42°,  was  dissolved  in 
about  4  liters  of  hot  water  and  treated  with  a  hot  solution  of  118  g.  of 
crystallized  barium  hydroxide  in  the  usual  way1  to  remove  brueine  from 
its  salts.  After  the  removal  of  brucine  by  filtration  and  extraction  of  the 
filtrate  with  benzol,  the  barium  was  removed  with  sulfuric  acid  and  the 
filtrate  from  the  barium  sulfate  was  subjected  to  complete  vacuum  dis- 
tillation. The  residue  was  taken  up  in  absolute  alcohol  and  the  solution 
was  filtered  to  remove  any  inorganic  salts  present.  The  alcohol  was  com- 
pletely removed  by  distillation  in  vacuo  finally  at  100°,  and  the  acid  was 
left  as  a  clear  yellow  and  very  mobile  oil. 

The  rotation  of  a  portion  of  this  acid  was  then  taken  and  another 
portion  was  titrated.  Other  portions  were  converted  into  the  barium 
and  calcium  salts  and  the  phenylhydrazid. 

Rotation. — The  specific  rotation  of  the  acid  in  approximately  4%  solu- 
tion was  found  to  be  — 8.29°,  i.  e.,  2.32  g.  acid  dissolved  in  45.78  g.  water 
gave  a  in  a  one  dcm.  tube  — 0.40°.  The  density  of  the  solution  was 
assumed  to  be  i.oo  and  the  temperature  was  approximately  20°. 

Titration. — The  titra.tion  showed  that  the  acid  was  present  largely  as 
lactone.  The  amounts  of  free  acid  and  lactone  were  determined2  and  the 
following  results  obtained. 

1  /.  Am.  Chem.  Soc.,  40,  981  (1918),  footnote  2. 

2  The  method  of  determining  the  free  acid  and  lactone  in  a  mixture  of  the  two 
is  as  follows.     The  weighed  sample  is  dissolved  as  rapidly  as  possible  in  cold  water  and 
immediately  titrated  to  pink  with  o.i   N  sodium  hydroxide  solution,  using  phenol- 
phthalein  as  indicator.     A  quantity  of  o.  i  N  sodium  hydroxide  solution  in  excess  of 


Weight  O.lA'NaOH      0.1  .V  NaOH  Total  Calc.  for  C< 

of  sample.  for  free  acid.        for  lactone.  NaOH  used.        saccharinic  acid. a 

G.  Cc.  Cc.  Cc.  Cc. 

I 0.4765  5-72  39-75  45-47  45,70 

II 0.4843  5.83  4076  46-59  4647 

0  In  calculating  the  theoretical  cc.  account  must,  of  course,  be  taken  of  the  amounts 
of  free  aoid  and  lactone  present  in  the  samples  as  indicated  by  the  titration  figures. 

These  titrations  show  that  about  14.4%  of  the  sample  in  water  solution 
exists  as  free  acid  and  the  rest  as  lactone.  This  agrees  with  Nef's  observa- 
tions.1 

The  Barium  Salt. — A  mixture  of  one  g.  of  acid.  3  g.  of  barium  carbonate 
and  75  cc.  of  water  was  heated  to  make  this  salt.  The  salt  was  gummy 
and  could  not  be  made  to  crystallize  except  by  triturating  with  absolute 
alcohol.  There  was  obtained  0.4  g.  of  the  vacuum-dried  salt ;  [a]&  + 1 .48  °, 
i.  e.,  0.4  g.  salt  in  9.6  g.  water  gave  a  +0.03°  in  a  half -decimeter  tube. 

The  Calcium  Salt. — A  mixture  of  1.2  g.  of  acid,  3  g.  of  calcium  carbonate 
and  75  cc.  of  water  was  heated  to  make  this  salt.  It  became  crystalline 
only  when  triturated  with  absolute  alcohol.  There  was  obtained  0.4  g. 
of  vacuum-dried  salt;  rotation,  [a\™  +2.47°,  i.  e.,  0.4  g.  of  salt  in  9.6  g. 
water  gav^e  a  +0.05°  in  a  half -decimeter  tube. 

The  Phenylhydrazid. — A  mixture  of  1.75  g.  of  acid,  2  cc.  of  phenyl- 
hydrazine  and  2  cc.  of  ethyl  acetate  gave,  in  the  usual  way  3.15  g.  of  the 
crude  phenylhydrazid.  This  was  recrystallized  from  18  cc.  of  ethyl 
acetate  and  gave  one  g.  of  phenylhydrazid  with  the  melting  point  of  102- 
103°.  This  was  recrystallized  from  3.7  cc.  of  ethyl  acetate  and  gave  0.75 
g.  of  crystals  with  a  melting  point  of  102-103°.  The  specific  rotation  of 
this  compound  was  found  to  be  +1.71°,  i.  e.,  0.54  g.  in  12.06  g.  of  water 
gave  a  +0.07°  in  a  one  dcm.  tube. 

The  Free  Acid  from  the  Non-crystallizable  Brucine  Salt. — The  mother 
liquor  from  the  4  crops  of  crystalline  brucine  salts  was  subjected  to  com- 
plete vacuum  distillation  at  60°  and  gave  a  residue  which  weighed  130  g. 
as  mentioned  above.  The  brucine  was  set  free  in  the  usual  way  and 
T5-25  g-  °f  a  light  brown  ether-soluble  oil  was  obtained.  The  specific 
rotation  of  this  acid  was  determined  as  +7.18°,  i.  e.,  1.65  g.  of  acid  in 
39.6  g.  of  water  gave  a  +0.287°  in  a  one  dcm.  tube.  As  the  specific 
rotation  of  the  optical  isomer  of  the  acid  from  the  brucine  salt  rotating 
—29.42°  should  be  +8.29°,  the  acid  now  under  consideration  was  evi- 

the  calculated  amount  is  then  added  and  the  mixture  heated  on  the  boiling  water-bath 
for  15  minutes.  It  is  then  cooled  and  a  measured  quantity  of  o.i  N  hydrochloric  acid 
is  added  to  acid  reaction  and  the  mixture  boiled  to  expel  carbon  dioxide.  It  is  again 
cooled  and  the  excess  hydrochloric  acid  is  determined  with  o.  i  N  sodium  hydroxide. 
solution.  The  quantity  of  sodium  hydroxide  solution  added  at  first  in  the  cold  de- 
termines the  amount  of  free  acid  present  and  the  remainder  added  determines  the 
-quantity  of  lactone. 

1  Ann.,  376,  35   (1910). 


dently  still  contaminated  with  some  of  the  racemic  acid.  It  was,  there- 
fore, converted  into  the  barium  salt.  The  15.25  g.  of  acid  yielded  14.8 
g.  of  the  vacuum-dried  barium  salt.  This  salt  had  a  specific  rotation 
of  — 148°,  i.  e.,  one  g.  of  salt  in  24  g.  of  water  gave  a  — 0.03°.  This 
indicates  that  the  salt  was  pure,  as  this  rotation  is  equal  and  opposite  to 
that  of  the  barium  salt  from  the  crystalline  brucine  salt.  The  gum  was 
set  free  from  this  salt  and  purified  in  the  usual  way.  The  weight  of  free 
acid  was  6  g.  It  was  a  light  yellow  mobile  oil. 

The  rotation  of  a  portion  of  this  acid  was  taken,  another  portion  was 
titrated  and  another  portion  was  converted  into  the  phenylhydrazid  with 
the  following  results. 

The  Rotation. — The  specific  rotation  of  the  acid  was  found  to  be  +8.00°, 
i.  e.,  0.83  g.  of  acid  dissolved  in  19.92  g.  of  water  gave  a  +0.32°  in  a  one 
dcm.  tube. 

The  Titration. — A  titration  of  another  portion  of  the  acid  gave  the 
following  results.  Only  one  titration  was  made  because  of  the  small 
amount  of  acid  available. 

Weight  O.lTVNaOH  O.lTVNaOH  Calc.  for  C4 

of  sample.  for  free  acid.  for  lactone.  Total.  saccharinic  acid. 

G.  Cc.  Cc.  Cc.  Cc. 

0.4014  6.l8  31.93          38.11        38.18 

The  Phenylhydrazid. — This  compound  was  obtained  only  as  a  gum, 
very  soluble  in  ethyl  acetate. 

Determination  of  the  Configuration  of  the  Two  Optical  Isomers.— 
The  foregoing  data  prove  that  the  <i/- 2,3-dioxy-butyric  acid  had  been 
separated  into  the  pure  dextro-  and  levo-rotating  components.  The 
next  step  in  the  problem  was  to  assign  the  proper  configuration  to  each 
of  the  new  acids.  It  was  shown  that  the  dioxy  acid  which  rotated  — 8.29^ 
could  be  oxidized  to  natural,  levo-rotating,  malic  acid.  The  malic  acids 
were  shown  by  Fischer1  to  have  the  configurations 

COOH  COOH 

I  I 

HO  —  C  —  H  H  —  C  —  OH 

!  "and  | 

H  — C  — H  H  — C  — H 

I  I 

COOH  COOH 

/-malic  or  natural  malic  acid.  rf-malic  acid. 

Of  the  two  2,3-dioxy-butyric  acids  under  consideration  only  one  could 
give  /-malic  acid  by  oxidation,  namely  the  one  with  the  configuration  I 
(see  below) .  The  acid  which  rotates — 8 .29°  then  must  have  this  configura- 
tion as  it  gives  /-malic  acid  and  must,  therefore,  be  called  /-2,3-dioxy- 
butyric  acid  while  the  acid  which  rotates  +8.00°  must  have  the  con- 
figuration II  (see  below)  and  must  be  called  d- 2,3-dioxy-butyric  acid. 
1  Ber.,  29,  1378  (1896). 


CH2OH  CH2OH 

I  I 

HOCH  HCOH 

1  I 

HCH  HCH 

I  I 

COOH  COOH 

(I).  (ID- 

The  experimental  evidence  for  these  conclusions  follows. 

Nef1  has  reported  on  the  oxidation  of  d/-2,3-dioxy-butyric  acid  to 
dl-ma\ic  acid.  We  repeated  Nef's  work.  As  our  procedure  differed 
somewhat  from  Nef's  it  is  given  below. 

The  d/-dioxy-butyric  acid  is  treated  with  10  times  its  weight  of  nitric 
acid  of  sp.  gr.  1.305  and  heated  for  2  hours  at  65°  in  a  water-bath.  The 
reaction  mixture  is  subjected  to  complete  vacuum  distillation  at  a  tem- 
perature not  exceeding  65  °.  The  residue — a  yellow  gum — is  dissolved  in 
10  to  12  times  its  weight  of  cold  water.  This  solution  is  treated  with  an 
excess  of  calcium  carbonate  and  this  mixture  shaken  for  10  to  15  minutes. 
The  excess  of  calcium  carbonate  is  then  removed  by  suction  filtration. 
The  filtrate  is  now  concentrated  by  boiling  to  about  1/2  its  volume  during 
which  process  the  normal  calcium  malate  separates.2  To  obtain  the  free 
d/-malic  acid  the  vacuum-dried  salt  is  suspended  in  a  large  volume  of 
hot  water  and  the  necessary  quantity  of  oxalic  acid,  calculated  on  the 
basis  of  an  analysis  of  the  vacuum-dried  salt,  is  added  in  hot  solution. 
The  mixture  is  kept  on  the  boiling  water-bath  for  3  hours  and  frequently 
shaken.  It  is  then  cooled  and  the  calcium  oxalate  is  separated  by  filtra- 
tion. The  filtrate  is  subjected  to  complete  vacuum  distillation  finally  at 
100°.  The  residue  is  extracted  3  times  with  boiling  ether.  The  com- 
bined filtered  ether  solution  is  completely  evaporated,  finally  on  the 
water-bath.  The  residue  is  placed  in  vacuo  over  sulfuric  acid  until  the 
weight  is  constant  when  the  malic  acid  remains  as  white  scales.  It  was 
proved  by  experiment  that  malic  acid  itself  is  not  appreciably  oxidized 
under  the  above  procedure. 

Five  and  two-tenths  g.  of  the  2,3-dioxy-butyric  acid  [a]i?  — 8.29,  was 
now  oxidized,  following  the  above  procedure  in  every  detail,  and  a  total  of 
2.15  g.  of  insoluble  calcium  salt  was  obtained.  Part  of  this  insoluble 
-calcium  salt  was  used  for  analysis  for  calcium  oxide  (see  below)  and  the 
acid  was  obtained  from  the  rest.  The  weight  of  acid  obtained  was  0.5 1 27  g. 
This  will  be  referred  to  hereafter  as  "free  acid." 

The  proof  of  the  identity  of  this  insoluble  salt  with  the  calcium  salt  of 
pure  natural  malic  acid  and  of  the  identity  of  the  "free  acid"  with  pure 
natural  malic  acid  was  brought  by  comparing  the  analyses  of  the  2  corre- 
1  Ann.,  376,  36   (1910). 
8  Ibid.,  233,  168  (1886). 


10 

spending  vacuum-dried  calcium  salts,  and  the  melting  points,  the  specific 
rotations  and  the  titrations  of  the  2  corresponding  acids.  The  natural 
malic  acid  was  recrystallized  from  ether.  Part  of  it  was  then  dried  in 
vacua  over  sulfuric  acid  and  part  was  converted  into  the  normal  calcium 
salt  by  the  procedure  described  above. 

Analysis  of  the  Calcium  Salts. — The  first  2  analyses  were  of  the  salt 
obtained  by  oxidizing  the  2,3-dioxy-butyric  acid,  the  last  2  of  the  salt  of 
pure  natural  malic  acid. 

Subs.,  0.2025,  0.2197,  0.2070,  0.1639:  CaO,  0.0661,  0.0712,  0.0670,  0.0530. 

Calc.  for  C4H4O5Ca:  CaO,  32.56..     Found:  32.65,  32.40,  32.36,  32.28. 

Melting  Points. — -The  melting  points  of  the  "free  acid,"  the  pure  natural 
malic  acid,  and  a  mixture  of  the  two  are  as  follows:  Melting  point  "free 
acid,"  96°;  natural  malic  acid,  95°;  mixture,  95-96°. 

The  Rotations. — The  specific  rotations  of  the  "free  acid"  and  of  the 
natural  malic  acid  were  taken  with  the  following  results. 

0.5117  g.  of  "free  acid"  in  12.3931  g.  water  gave  a  — 0.13°  in  a  one  dcm.  tube. 
0.6588  g.  of  natural  malic  acid  in  15.8939  g.  water  gave  a  — 0.126  in  a  one  dcm. 
tube. 

[«]2D  of  "free  acid."  [<*]2D  °f  natural  acid. 

—3-46°  —3.18° 

The  Titrations. — Samples  of  the  "free  acid"  and  of  the  natural  acid 
were  titrated  with  the  following  results. 

Weight  0. 1  N  NaOH  for  neutralization. 

of  sample. 


G.  Found.    Cc.  Calc.    Cc. 

I o  1533  ^22.91  22.83 

II 0.1177  17.38  17.57       * 

HI *.-.       0.1671  24.77  24.94 

The  first  and  second  titrations  were  made  with  the  "free  acid"  and  the 
third  titration  was  made  with  the  natural  acid. 

Summary. 

d/-2,3-Dioxy-butyric  acid  from  glycerol-a-monochloro-hydrine  has  been 
prepared.  Proof  of  the  structure  of  .dl- 2,3-dioxy-butyric  acid  is  given  by 
its  preparation  from  vinyl-acetic  acid,  CH2  :  CH.CH2COOH.  The 
resolution  of  the  J/-acid  into  the  optical  components  by  the  use  of  brucine 
is  reported.  Configurations  are  assigned  to  the  2  forms  of  the  acid  and 
proofs  of  the  correctness  of  these  configurations  given.  The  following, 
specific  rotations  for  the  d-  and  /-forms  of  the  acid  and  some  of  the  deriva- 
tives are  given. 

Free  acid:  Barium  salt.  Calcium  salt.  Phenylhydrazid. 

d-form +8.00°  —1.48°  

/-form —8.29°  +1.48°  +2.47°  +1.71° 


. 


Syracuse,  N.  Y. 
PAT.  JAN.  21, 1908 


45868^ 


UNIVERSITY  OF  CAUFORNIA  LIBRARY 


